Guano (Bird excreta)Guano is the accumulated excrement or droppings of fish eating sea birds such as gannets, cormorants and pelicans. It has been used as a fertilizer. These sea birds populate some islands off the west coast of Peru, lower California and Africa. Their population strength may go upto 5, 600, 000 per square mile. They may consume 1000 tonnes of fish daily. Exports of guano from the Peruvian deposits began in 1810 and reached 50, 000 tons in 1856. The Government protects the seafowls and processes the guano which contains about 11 to 16% nitrogen, 8 to 12 % phosphoric acid and 2 to 3% potash. The fertilizing properties of the phosphoric acid and nitrogen contained in fish were not recognised until the guano became a stimulus to intensive agriculture. The real guano is found in vast stratified accretions on rainless islands off the coasts of Peru.
Aquarium Next to birds fishes are perhaps the most colourful of animals. They are graceful in their shape, bodyform and movement. The Chinese first conceived the idea of growing fishes in and around their homes. Thus, varieties of gold fishes which are popular with aquarium lovers were bred by them from ordinary carplike fishes. Gold fishes are varieties of the genus Carassius, a fresh water group of fishes related to the carps. An Aquarium is a container made of glass, or with glass walls. It permits watching the fishes swimming easily and for prolonged periods of time. It is a hobby which appeals to young and old and has opened up a flourishing business in all big cities.
Setting up an aquarium tank
Tank selection : The choice of an aquarium tank, depends largely on where it is to be housed, the extent of one’s enthusiasm and the money one wants to spend. While selecting a tank it is very important to note that it is of good construction. Shallow and wide tanks are preferable as they have more surface area to facililate oxygenation through atmospheric contact. Further such tanks can accomodate more number of fishes.
Before setting up the tank, a suitable place has to be selected. In order to get a good view of both fishes and plants in an aquarium tank, the light should come obliquely. Hence, instead of the window sill, a place nearer to its side may be selected. To avail maximum sunlight an eastern exposure is preferable. The support or table for positioning the tank must be strong and in level. It is also essential to have a cover with a provision for installing lights and feeding.
If the tanks are purchased they should be checked for leakage. Their sides should be cleaned with 1 % potassium permanganate solution, besides repeated washing with tap water. The next step in the setting up of an aquarium is the collection of sand that is necessary to make the bed at the bottom of the tank. The sand for the tank bottom can be collected from the sea shore or a river. This sand has to be washed to remove the dirt. It is advisable to put the sand in a shallow pan or aluminium vessel and heating it. The cleaned sand may be exposed in the bright sun. These processes ensure the killing of all bacteria or germs. The cleaned sand should be spread evenly in the tank bottom. Over the top layer of sand a thin layer of stone chips or very small pebbles may be placed.
Quality of water for Aquarium tank Rain water free from contaminants or tap water is ideal for aquarium tanks. A tap water of domestic supply is likely to have chlorine which is harmful to fish. This water may be stagnated for about one or two days before use. If the water is hard it must be properly treated. The tank should be filled with the desired water without disturbing the bottom sand.
Planting : The aquarium tank after being filled with water can be planted with selected varieties of aquatic plants. The plants provide shade, shelter and sanctuary for fish. Besides decorating the aquarium tank, they also help in spawning and as food for certain fishes. The plants provide oxygen through photosynthesis. Over crowding of plants has to be avoided to ensure an adequate supply of oxygen to fishes. Several types of plants are available. Among them the important ones are the tall rooted plants such as Vallisneria and Myriophyllum. Before planting, the plants must be washed well otherwise disease causing parasites may attack the fish at a later stage. Plants may be disinfected by rinsing in 0.1 percent solution of alum (Potassium aluminium sulphate) followed by a good washing in water. The roots are trimmed and are kept between wet newspaper sheets to prevent them from drying before they are set. The plants are carefully installed using a forked wooden piece. Large plants like vallisneria may be planted at the back while the bushy plants can be placed in the corners or at sides. The floating plants may be necessary in tanks where gouramies are bred. The fragments of these plants are used by these fishes in the construction of bubble nests for breeding.
Lighting : Light besides beautifying the aquarium helps in the photosynthesis of aquarium plants. Fishes also require light to trace their food. Further the light is known to influence the growth of fish. Strong sunlight destroys bacteria and keeps the tank healthy. For a moderate tank two bulbs of 60 watts each may be lit for eight hours a day. It is better to use fluorescent lighting for promotion of plant growth and for even distribution of light
Common ornamental fishes
Guppy - Lebistes reticulatus
Platy - Xiphophorus maculatus
Sword tail - Xiphophorus helleri
Black molly - Mollienesia sphenops
Siamese fighter - Betta splendens
Giant gourami - Colisa fasciata
Kissing gourami - Helostoma temmineki
Angel fish - Pterophyllum scalare
Gold fish - Carassius carassius
Introduction of fish in an aquarium tank.
The number of fishes suitable for stocking in an aquarium tank depends mainly on the surface area of the tank, its dissolved oxygen content and size of the fish. It is reported that 1 cm long fish may need about 75 cm2 of the surface area. Based on the above, a tank of 75 X 30 cm size for example may hold three fishes each of 10 cm length. The fishes are generally introduced two to three days after planting when the water would be clear and well oxygenated by plants. Before introduction into the aquarium tank, the fish may be treated with 2 percent potassium permanganate solution to avoid parasitic attack.
Feeding Algae which often grow around stones and in water serve as a good food source to swordtails, kissing gourami and mollies. Live protein rich foods such as tubifex worms, Chironomid larvae and mosquito larvae are considered excellent. Artificial fish feed meant only for aquarium fishes can also be used. Fishes may be fed once or twice a day according to their preference and satiation. Excess food and detritus may be removed 30 minutes after feeding, by siphoning out using a rubber tubing. If the level of the water gets reduced in course of time it should be restored by the addition of some rain water or chlorine free tap water.
Aesthetic value : A large number of fishes are cultured in aquaria for their beauty and graceful movements. The movements of colour fishes in an aquarium would certainly please the ailing and convalescing people. The aquarium may gladden one’s heart.
Vivarium ( Zoo ) The growing awareness for nature and wild life conservation has made zoos a popular institution. Estimates indicate that 10% of the world’s human population visit zoos every year. There are about 350 animal collections in India, which are visited by more than 50 million people annually. Most zoos until the last two decades were set up mainly for entertainment and recreation, with the result the scientific management of wild animals in captivity has evolved slowly.
The need for making conservation as one of the main objectives of management of zoos was realised by Government of India soon after independence. Indian Board of wild life made important recommendation in this regard. Today wildlife habitats are under severe pressure and a large number of species of wild fauna have become endangered. The zoos apart from sustaining their own populations have to augment the depleting populations of endangered species in the wild. As zoos are visited by a large number of visitors, they are potent tools for educating people about the important of wild life management as it remain a life supporting processe of nature
The main objective of the zoos shall be the conservation of the rich biodiversity of the country, particularly the wild fauna. This objective can be achieved through the following methods.
1. Supporting the conservation of endangered species, which have no chance of survival in wild.
2. To inspire amongst zoo visitors empathy for wild animals, an understanding and awareness about the need for conservation of natural resources and for maintaining the ecological balance.
3. Providing opportunities for scientific studies useful for conservation
Safari :- Safaris are specialized zoos where the captive animals are housed in very large naturalistic enclosures and the visitors are allowed to enter the enclosure to view the animals in a mechanised vehicle or a predetermined route and watch the animals from close quarters.
List of important Zoos
1. Indira Gandhi Zoological park, Visakha patnam, A. P.
2. Nehru Zoological park, Hydrabad, A. P.
3. Assam state Zoo-Botanical Garden, Guwahati, Assam.
4. Sanjay Gandhi Biological park, Patna, Bihar.
5. National Zoological park, Delhi.
6. Kamla Nehru Zoological Garden, Ahmedabad, Gujarat.
7. Sri Chamarajendra Zoological Garden, Mysore.
8. Nandankanan Biological park, Orissa
9. Mahendra Chaudhury Zoological park, Punjab.
10. Arignar Anna Zoological park, Vandalur, Tamil Nadu.
11. Kanpur Zoological park, Kanour, U. P.
12. Zoological Garden, Calcutta.